my Sheevaplug is constantly powered on for a couple of months now (240VAC, although limited to around 230VAC by UPS) and the repeated stories about failing power supplies make me expect mine to fail pretty soon. Instead of hooking up an external PSU, I'm planning to replace the capacitors with better ones before they dry out completely.

However, I use this box as my central home server (email, DNS, Internet, ...) and I'm afraid that the capacitors have aready degraded to the point where it won't turn on after I opened it up to find out which capacitors I actually need...

Does anyone of you have a list of capacitors (capacity, voltage and approximate size) in the Sheevaplug PSU?

While waiting for a reply, I guess I'll try and see whether I can get a backup of the plug's root disk working on my desktop under qemu-system-arm -- I always wanted to see whether this is a viable solution for temporarily replacing the plug with a desktop while getting the plug itself fixed...

The problem with the capacitors is not that they dry out, but that the liquid electrolyte in the capacitors heats up due to the electrolyte conducting ac ripple current and heating, eventually blowing the electrolyte out through the overpressure vent, (the radial frangible lines on the end of the capacitor).

The "goodness" or ESR (equivalent series resistance), of the capacitor can vary with age and ambient temperature, normally upwards. The heating effect is Watts = (Iripple) squared x ESR , or the heating effect is directly proportional to the value of the ESR.

This is a mains switching power supply. It can give you a nasty shock. MAINS IS CONNECTED DIRECTLY TO THE CAPACITOR WITH NO SAFETY ISOLATION. Please make sure that the PS is disconnected from the mains and the caps are discharged BEFORE you work on the supply.

The capacitors in the Sheevaplug V 1.3 ( second generation) 's power supply:-

I can only second your warnings for everybody reading this. I once ruined a screwdriver discharging a high-voltage capacitor in an old valve radio. I thought the capacitor had already discharged and just wanted to play it safe but it must have had the full charge for such an effect and this would mean around 311V (220VAC in Germany back then). These days we have 240VAC/340V peak...

Back to the subject: so you would say only those two capacitors need replacing? I was wondering whether I should replace all of them while I'm at it... Also, do you remember the size of those two (diameter and height)?